Movable rack assemblies are known for storing quantities of materials such as work folders. Typically, each rack assembly is guided by a plurality of rails or guide tracks located in or on the floor. A manually rotated drive assembly is sometimes used to move a plurality of racks relative to stationary or fixed racks, which are typically located at opposite ends of the movable racks. The track or guide system located in or on the floor is usually of a design shaped complementary to the wheels, rollers or other conveyance mechanisms used to move the various racks.
It is also possible to use an overhead rail system, typically including a horizontally oriented roller restrained within the side walls of a guide rail system. On the occasion where a vertically oriented roller is used, it is typically used in conjunction with horizontally oriented rollers.
Alternatively, in one known system, when using only vertically oriented wheels, a guide support rail having a precisely adjusted height is used. The rail is positioned so that the vertically extending wheels engage and are supported from underneath by a vertically lower portion of the rail.